Unloader for air compressors



Oct. 19 1926.

1,603,495 v E. A. RlX

-UNLOADER FOR AIR COMPRESSORS I Filed April 15, 1925 2 Sheets-Sheet l hue/mar im/7w; w, S By M/ W flzrcomcgs.

Patented Oct. 19, 1926.:

PATENT, OFFIQE.

EDWARD A. RIX, or SAN rnanorsco, cALrroBNm.

UNLOA'DER FOR AIR GOMPRESSORS.

Application filed April 13, 1925. Serial m. 22,644. 1'

This invention relates to an air compres- S01, and particularly to an automatically actuated discharge unloader therefor.

The present invention embodies in combination an air-compressor, a tank or receiver connected therewith to which the compressed air is delivered, a discharge unloader interposed between the compressor and the receiver, a motor for driving the compressor, and means co-operating with the unloader for regulating the speed of the motor. I

' The object of the present invention is to provide an improved form of unloader, to provide means for automatically actuating the same when predetermined pressures are obtained in the receiver, and further, to provide means operatable in conjunction with the unloader for regulating the speed of the driving motor.

One form which the invention may as sume is exemplified in the accompanying drawings, in which- Fig. 1 is a side elevation, showing an assembly of. driving motor, air compressor, air receiver, .and unloader.

Fig. 2 is a central verticalsection of the unloader.

Referring to the drawings in detail, and particularly Fig. 1, A indicates a. motor of the internal combustion engine type; B a multicylinder air compressor; 0 a tank or receiver to which the compressed air is delivered; and D an automatically actuated unloader. The unloader serves two functions: first, that of Toy-passing the air discharging from the compressor when a predetermined pressure is obtained within the The unloader consists of two main casings indicated at 2 and 3. The lower casing 3 is provided with a centralchamber 4.- The -casing is provided with two connections, one

indicated at 5 and one at 6. The air discharging from the compressor is delivered to the central chamber 4 through the connection .5, while the air which is to be delivered to the receiver is discharged through the connection 6. The air passes through a pipe 7 and enters the receiver at the point r indicated at 8. The bottom of the casing 3 is provided with a plurality of discharge ports generally indicated at 9 and 10. Se-

receiver :v and secondly, that of regulating.

36 engages the lower face of the diaphragm;

a valve which engages a seat 37.

cured to the bottom section is a retainer disc 11, and interposed between the disc and the ports 9 and 10 are two sets of ring valves 12 and 13, and co-ope'rating springs 14. These valves operate in unison and serve the function of check-valves, and the only reason for employing two sets of valves is to increase the area, so that the air may discharge with the least resistance. possible. The bottom portion 15 of the upper casing 2 is also provided with a series of ports," as indicated at 16, and an unloader valve generally indicated at 17 normally closes these ports, said valve being held in closed position by means of a spring 18. The unloader valve is automatically opened when a pre determined pressure is obtained in the receiver C, and air discharging from the com- 7 pressor and entering the chamber 4 through 75 the connection 5 will in that case discharge through the ports 16 and enter the central chamber 19. The air escapes from this chamber into a secondary chamber 20, as will opening 21.

The mechanism whereby the unloader valve 17 is opened will now be described. By referring to Fig. 2, it will be noted that the casing 2 is provided with a cover. plate 22. A diaphragm 23 is interposed between the cover plate and the casing, and two chambers are thus formed, as indicated'at 24 and 25. Forming an extension of the unloader valve 17 is an upwardly extending stem 26, and mounted on the upper end thereof and engaging the diaphragm 23 is a button disc 27. Formed in the cover is a centrally threaded opening 28, and adapted to be screwed therein or otherwise secured, is a pilot valve generally indicated at F. The pilot valve consists of two casings, as indicated at 30 and 31. A diaphragm s interposed between the two casings, as indicated at 32, a button 33 engages the upper side of the diaphragm, and a pressure-regulating spring 34 is interposed between thebutton and an adjusting screw 35. A valve 106 that is, the upper end of the valve is provided with a head which engages the diaphragm, while the lower end thereof forms An alr receiving chamber is formed between the lower face of the diaphragm and the casing 31, as indicated at 38, and this chamber is in valve 36 will also lift, as it is raised inde pendently of the diaphragm by means of the spring 41. The air under pressure will, under these conditions, pass by the valve 37, and will enter the upper chamber 24. It will here exert a pressure on the diaphragm 23 and will cause this to deflect in a downward direction. This movement of the diaphragm is transmitted to the button 27 and the valve stem 26, and the unloader valve is thus lowered with relation to the ports 16: or in other words, moved to open position. The

air discharging from the compressor and en-- tering the chamber 4 will thus discharge.

through the ports 16 into the chambers 19 and 20, and thus will. finally escape to the atmosphere through the pipe 21. The check valves 12 and 13 will not open when the unloader valve is opened, as'they are held against their seat not only by the springs 14 but also by the air pressure exerted against them, which in this instance would be 120 pounds. If the pressure in the main receiver drops below 120 pounds, the'spring 34 instantly responds, and forcesthe diaphragm 32 back to normal position. This movement causes valve 36 to close, and diaphragm 23 is thus also permitted to return to normal position, as it will be relieved of pressure. The unloader valve 17 will close, due to the return movement of the diaphragm, and also due to the upward pressure of the spring 18,

and the air discharging from the compressor and entering the chamber 4 through the connection 5 will then pass through the check valves 9 and 10 and again enter the main receiver.

When a compressor such as here illustrated is driven by a gasoline motor, for instance in portable outfits, it is desirable as a matter of economy in the matter of fuelrand wear and tear, to slow downthe motor at the time the discharge unloader acts. This is accomplished by means of a kick-oft control con-' sisting of a piston 50 which is mounted in a cylinder 51 formed in the'upper casing 2. The inner end of the cylinder is in communication with the central chamber 19.. The outer end of the cylinder is closed by a head 52, and a piston rod passes therethrough, as

, shown-at53, this piston-rod being connected with the piston 50. A spring is interposed between the head 52 and the piston'50 as shown at 54, and the piston 50 therefore normally assumes the inner position shown in Fig. 2. The outer end of the piston rod is connected through means of a rod 55 with the throttle valve lever 56 of the motor. When piston 50 assumesthe innermost position shown in Fig.2, throttle valve 56 assumes open position, and the motor is able to operate under full speed and load. When piston 50 assumes its outermost position, as will hereinafter be described, the throttle valve 56 is substantially closed, and the motor will therefore operate under practically no load and at a fairly low speed. That is,

the no-load condition is due to the fact that the compressor is freely discharging its air to the atmosphere at this time The piston 50, which actuates the throttle valve of the motor, might be termed a speed-regulating device, as it slows down the speed of the motor to low throttle speed when the compressor is discharging its air to the atmosphere,

and it alsomoves the throttle valve to full load and maximum speed position when the compressor is in operation. The operation pf the speed-regulating device will be as folows:

When the unloader valve 17 opens after the predetermined pressure has been obtained in the main receiver, the air, as previously stated, discharges from the compressor into" the central chamber 4 and then passes through portsl6 into the central chamber 19. Cylinder 51 is in direct communicationwith this central chamber, and the air under pressure discharging from chamber 4 into chamber 19 will force the piston 50 to its outermost position. A discharge port 60is formed in the cylinder 51 and this discharge port is completely uncovered or opened when the piston 50 assumes its outermost position. Port 60 'communicates with the secondary chamber 20,

and the air will thus freely escape into the chamber 20 and then to the atmosphere through pipe 2 1.

It will be noted that a perforated plug 61 also forms a connection between the chambers 19 and 20, and that the air will thus also escape through the plug. This plug is merely provided for the purpose of cush1on ing or preventing a too rapid outward movement of the piston 50. When the unloading valve 17 opens and the air enters the secondary chamber 19, the pressure is so great that the piston 50 will be thrown to its outermost position in the smallest fraction of a second. This speed is too rapid, and might cause damage to the piston. It is for this reason that the perforated plug 61 is provided, as it lowers the" pressure by permitting part of the air to escape while the piston 50 is being forced outwardly. It will also be noted that chamber 24is vented as indiair delivered to the chamber 24 by the pilot valve 36 must be released so that the dia-' phragm 23 can return when the pilot valve closes. The vent isexceedingly small, and for this reason permits only a very small amount of air to escape when the unloader valve is in operation.

From the foregoing it will be seen that I have provided an unloader which permits the air from the compressor to be freely discharged to the atmosphere when a predetermined pressure has been obtained in the main tank or receiver; that means are employed for automatically actuating the unloader; and that means are provided which co-operate with the unloader to regulate the speed of the driving motor. The unloader constructed as here illustrated is not af-- fected by temperature variations, and may as aconsequence be placed as close. as de.

sired to the discharge of the compressor. The main diaphragm 23 has a comparatively small movement, and is, practically speaking, leak-proof. A small pilot valve such as shown at F may be employed, and sensitive action and economical use of the air is obtained. While certain featuresof the presentinvention are more or less specifically illustrated, I wish it understood that va. rying changes may be made within the scope of the appended claims. Similarly, that the materials and finish of the several parts employed may be such as the experience and judgment of the manufacturer may dictate. Having thus described my invention, what I claim as new and desire to secure by Let ters Patent is:

1. The combination with an air compressor and a tank or receiver connected therewith, of an'unloader interposed between the compressor and the receiver, a motor adapted to drive the compressor, and means in the unloader for regulating the speed of the motor and compressor and for simultaneously diverting the air from the compressor to the atmosphere when a predetermined air pressure is obtained in the receiver.

2. The combination with an air compressor and a tank or receiver connected therewith, of an unloader interposed between the compressor and the receiver, an unloader valve in the unloader, a cylinder in the unloader, a piston therein, a motor adapted to drive the compressor, and means wherebythe unloader valve is opened when a predetermined air pressure is obtained in the receiver, said means also admitting air under pressure to the cylinder and piston and imparting movement to the piston, and means actuated by the movement of the piston for regulating the speed of the motor and the compressor.

3. An unloader of the character described, comprising a casing, a check valve therein, an unloader valve therein, a diaphragm, means actuated by movement of the diaphragm for opening the unloader valve, a cylinder chamber formed in the unloader, a piston mounted therein, means actuated by opening of the unloader valve for delivering air under pressure and imparting movement to the 'said piston, and a pilot valve adapted to deliver air under pressure to actuate the diaphragm.

4. An unloader of the character described,

comprising a casing, a check valve therein, an unloader valve thereln, a diaphragm,

means actuated by the movement of the diaphragm for opening-the unloader valve, a cylinder chamber formed in the unloader,-a piston mounted therein, means actuated by opening of the unloader valve for delivering air under pressure and imparting movement to the said piston, means for regulating the speed of the piston, and a pilot valve adapted to deliver air under pressure to the diaphragm to actuate the same.

5. An air compressor unit comprising an internal combustion engine, a compressor driven thereby, an air receiver connected with the compressor, an unloader interposed between the compressor and the air receiver, means actuated by a predetermined pressure in the air receiver for diverting air from the compressor to the atmosphere, and other means actuated by said predetermined air pressure for regulating the speed of'the internal combustion motor and the air compressor driven thereby.

' EDWARD A. RIX. 

